1. Field of the Invention
The present invention relates to a rotating electrical machine such as a motor or a generator or the like, and to a method for manufacturing a stator of a rotating electrical machine.
2. Description of Related Art
As constructions for the coils to be employed for the stator of a rotating electrical machine, the concentrated winding format and the distributed winding format and so on are per se known. In the concentrated winding, a coil for one phase is wound upon a single core tooth, and therefore this has the advantage that it is possible to make the coils more compact, as compared with the case of a distributed winding. On the other hand, in the case of the distributed winding, a coil for one phase is subdivided into a plurality of coils and each subdivided coil is wound so as to straddle several core slots, and therefore this has the advantage that the electrical characteristics are better, as compared with the case of the concentrated winding. It should be understood that the coils are wound around the teeth with interposition of insulating material.
Furthermore, from the point of view of the positional relationship between the stator and the rotor, rotating electrical machines can broadly be divided into the inner-rotor type in which the rotor rotates in the interior of the stator, and the outer-rotor type in which the rotor rotates over the exterior of the stator. In the case of the inner-rotor type, in general, the rotor is linked to a main shaft that transmits rotation, while, in the case of the outer-rotor type, in general, the rotor is linked to or is integrated with a rotating element that is to be directly driven, or indirectly drives a rotating element via a gear wheel or the like.
For example, in the case of the outer-rotor type, a construction may be employed in which coils are installed into core slots from the exterior of the stator core. The stator core is fabricated by laminating a plurality of magnetic steel plates, and with such a stator core, it is desirable for the stator core to be of an integrated type from the viewpoint of reduction of iron loss; and moreover, from the viewpoint of reduction of copper loss in the coils, whichever of the concentrated winding and the distributed winding is employed as the coil winding method, it is desirable for the space factor of the coils in the slots to be high, by which the cross section of coil wires in each slot can be increased and therefore the coil resistance can be reduced.
With the technique described in Japanese Laid-Open Patent Publication H10-304609, in an outer-rotor type rotating electrical machine, in order to make the task of winding the coils upon the stator core simple and easy and in order to enhance the space factor, upon one of each pair of adjacent teeth, magnetic pole pieces are provided as projections that extend in the radial direction from both its sides at its end via thin link portions, and, after the coils have been wound, these thin link portions are bent around so that the magnetic pole pieces are displaced to extend in the circumferential direction. Furthermore, with the technique described in Japanese Laid-Open Patent Publication 2001-136701, it is arranged to provide projections on the ends of the teeth.